pyrolite: Python for geochemistry

Williams, Morgan; Schoneveld, Louise; Mao, Yajing; Klump, Jens; Gosses, Justin; Dalton, Hayden; Bath, Adam; Barnes, Stephen J.

doi:10.21105/joss.02314

Cited by 39 publications

(32 citation statements)

References 14 publications

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“…Colored fields indicate areas within 95% confidence interval from kernel density estimates (KDEs); points on the Th‐3Tb‐2Ta diagrams indicate average compositions plotted on the normalized multi‐element diagrams. Plots for intraoceanic back‐arcs show KDEs created using the software pyrolite (Williams et al., 2020), with darker blues indicating greater density/probability and lighter blues indicating lower density/probability. Sources: depleted mid‐ocean ridge basalt (D‐MORB), enriched mid‐ocean ridge basalt (E‐MORB), intraoceanic back‐arcs—Gale et al.…”

Section: Geochemistry Of Modern Continental Back‐arc Basinsmentioning

confidence: 99%

A Preliminary Framework for Magmatism in Modern Continental Back‐Arc Basins and Its Application to the Triassic‐Jurassic Tectonic Evolution of the Caucasus

Vasey

Cowgill

Cooper

2021

Geochem Geophys Geosyst

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Extension within a continental back‐arc basin initiates within continental rather than oceanic lithosphere, and the geochemical characteristics of magmatic rocks within continental back‐arcs are poorly understood relative to their intraoceanic counterparts. Here, we compile published geochemical data from five exemplar modern continental back‐arc basins—the Okinawa Trough, Bransfield Strait, Tyrrhenian Sea, Patagonia plateau, and Aegean Sea/Western Anatolia—to establish a geochemical framework for continental back‐arc magmatism. This analysis shows that continental back‐arcs yield geochemical signatures more similar to arc magmatism than intraoceanic back‐arcs do. We apply this framework to published data for Triassic‐Jurassic magmatic rocks from the Caucasus arc system, which includes a relict continental back‐arc, the Caucasus Basin, that opened during the Jurassic and for which the causal mechanism of formation remains debated. Our analysis of 40Ar/39Ar and U‐Pb ages indicates Permian‐Triassic arc magmatism from ∼260 to 220 Ma due to subduction beneath the Greater Caucasus and Scythian Platform. Late Triassic (∼220–210 Ma) collision of the Iranian block with Laurasia likely induced trench retreat in the Caucasus region and led to migration of the Caucasus arc and opening of the Caucasus Basin. This activity was followed by Jurassic arc magmatism in the Lesser Caucasus from ∼180 to 140 Ma and back‐arc spreading in the Caucasus Basin from ∼180 to 160 Ma. Trace element and Sr‐Nd isotopic data for magmatic rocks indicate that Caucasus Basin magmatism is comparable to modern continental back‐arcs and that the source to the Lesser Caucasus arc became more enriched at ∼160 Ma, likely from the cessation of back‐arc spreading.

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Section: Geochemistry Of Modern Continental Back‐arc Basinsmentioning

confidence: 99%

A Preliminary Framework for Magmatism in Modern Continental Back‐Arc Basins and Its Application to the Triassic‐Jurassic Tectonic Evolution of the Caucasus

Vasey

Cowgill

Cooper

2021

Geochem Geophys Geosyst

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“…It is accessible at https://lambdar.rses.anu.edu.au/blambdar/. The second is pyrolite, a Python package which includes functions for fitting lambdas and tetrads amongst a suite of tools tailored to transformation and visualisation of geochemical data (Williams et al 2020).…”

Section: Combining λ and τ Shape Coefficientsmentioning

confidence: 99%

“…Data Availability Statement Data supporting this research can be generated interactively using the opensource online apps ALambdaR and BLambdaR available at https://lambdar.rses.anu.edu.au/alambdar and https://lambdar.rses.anu.edu.au/blambdar, or using the Python package pyrolite available at https://pyrolite. readthedocs.io/ (Williams et al 2020). Input parameters and references are given in this article at the relevant locations.…”

Section: Declarationsmentioning

confidence: 99%

Quantifying the Tetrad Effect, Shape Components, and Ce–Eu–Gd Anomalies in Rare Earth Element Patterns

Anenburg

Williams

2021

Math Geosci

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Plots of chondrite-normalised rare earth element (REE) patterns often appear as smooth curves. These curves can be decomposed into orthogonal polynomial functions (shape components), each of which captures a feature of the total pattern. The coefficients of these components (known as the lambda coefficients—$$\lambda $$ λ ) can be derived using least-squares fitting, allowing quantitative description of REE patterns and dimension reduction of parameters required for this. The tetrad effect is similarly quantified using least-squares fitting of shape components to data, resulting in the tetrad coefficients ($$\tau $$ τ ). Our method allows fitting of all four tetrad coefficients together with tetrad-independent $$\lambda $$ λ curvature. We describe the mathematical derivation of the method and two tools to apply the method: the online interactive application BLambdaR, and the Python package pyrolite. We show several case studies that explore aspects of the method, its treatment of redox-anomalous REE, and possible pitfalls and considerations in its use.

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“…Six further outliers were iteratively removed from PCA analysis, for a final total of 24 samples used (Table S2). Data analysis and visualisation employed the pandas [89], pyrolite [90], matplotlib [91], mpltern [92], and seaborn [93] packages for the Python programming language.…”

Section: Principal Component Analysismentioning

confidence: 99%

Iron Isotopes Reveal a Benthic Iron Shuttle in the Palaeoproterozoic Zaonega Formation: Basinal Restriction, Euxinia, and the Effect on Global Palaeoredox Proxies

et al. 2021

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The Zaonega Formation in northwest Russia (~2.0 billion years old) is amongst the most complete successions that record the middle of the Palaeoproterozoic era. As such, geochemical data from the formation have played a central role in framing the debate over redox dynamics in the aftermath of the Great Oxidation Event (GOE). However, uncertainty over local redox conditions and the degree of hydrographic restriction in the formation has led to contradictory interpretations regarding global oxygen (O2) fugacity. Here, we provide new iron (Fe) isotope data together with major and trace element concentrations to constrain the local physiochemical conditions. The Zaonega Formation sediments show authigenic Fe accumulation (Fe/Al ≫ 1 wt.%/wt.%) and δ56Fe ranging from −0.58‰ to +0.60‰. Many of the data fall on a negative Fe/Al versus δ56Fe trend, diagnostic of a benthic Fe shuttle, which implies that Zaonega Formation rocks formed in a redox-stratified and semi-restricted basin. However, basin restriction did not coincide with diminished trace metal enrichment, likely due to episodes of deep-water exchange with metal-rich oxygenated seawater, as evidenced by simultaneous authigenic Fe(III) precipitation. If so, the Onega Basin maintained a connection that allowed its sediments to record signals of global ocean chemistry despite significant basinal effects.

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pyrolite: Python for geochemistry

Abstract: pyrolite is a Python package for working with multivariate geochemical data, with a particular focus on rock and mineral chemistry. The project aims to contribute to more robust, efficient and reproducible data-driven geochemical research.

Cited by 39 publications

References 14 publications

A Preliminary Framework for Magmatism in Modern Continental Back‐Arc Basins and Its Application to the Triassic‐Jurassic Tectonic Evolution of the Caucasus

A Preliminary Framework for Magmatism in Modern Continental Back‐Arc Basins and Its Application to the Triassic‐Jurassic Tectonic Evolution of the Caucasus

Quantifying the Tetrad Effect, Shape Components, and Ce–Eu–Gd Anomalies in Rare Earth Element Patterns

Iron Isotopes Reveal a Benthic Iron Shuttle in the Palaeoproterozoic Zaonega Formation: Basinal Restriction, Euxinia, and the Effect on Global Palaeoredox Proxies

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